Water: a Limited Resource

Chapter 13 Water: A Limited Resource

A. Properties of Water a. Composed of 2 Hydrogen and 1 Oxygen b. Exists as a solid, liquid or gas c. High heat capacity d. Is polar e. Forms hydrogen bond between 2 water molecules e.i. Hydrogen bonds define water’s physical properties f. Water is never completely pure in nature-contains dissolved gasses from the atmosphere and dissolved mineral salts g. Many pollutants dissolve in water B. Hydrologic Cycle and our Supply of Fresh Water a. Water continuously circulates through the environment, from the ocean to the atmosphere to the land and back to the ocean. b. Only 2.5% of water on earth is fresh water and most of that is leaving only %0. 5 available fresh water c. Surface Water- Precipitation that remains on the surface and does not seep into the soil d. Runoff- Movement of surface water to lakes, rivers, etc. e. Watershed (drainage basin)- Land area that delivers water into a stream or river system f. Groundwater- Freshwater under the earth’s surface stored in aquifers g. Aquifer- Underground cavers and porous layers of sand, gravel and rock in which groundwater is stored C. Water Use and Resource Problems a. To much water a.i. Flooding both natural and human induced a.ii. Modern floods are highly destructive because humans have removed water-absorbing plant cover from the soil and construct buildings on floodplains a.iii. Floodplain- Area bordering a river channel that has the potential to flood b. To Little Water b.i. Typically found in arid land b.ii. Drought, overdrawing water for irrigation b.iii. Aquifer depletion causes subsidence and sinkholes b.iv. Saltwater intrusion-The movement of seawater into a freshwater aquifer located near the coast-caused by aquifer depletion D. Water Problems In US and Canada a. US has a plentiful supply of fresh water as compared to other countries b. Many areas of the US have sever shortages due to geographic location (desert) and seasonal variations in weather c. Water shortages a severe in the West and Southwest US so water is diverted and transferred via aqueducts d. Mono Lake, CA- Rivers and streams that once fed this lake are diverted to Los Angles. The lake is becoming highly saline. e. Colorado River Basin- Provides water for more then 30 million people. Have numerous dams for hydropower. Colorado river no longer reaches the Ocean as a result of its waters diversions. f. Conservation-based Pricing- Water supply pricing structure that rewards customers for using less water. These often come in the form of low process for water uses up to some level and stepped-up prices as use increases g. Groundwater g.i. Aquifer depletion g.ii. Ogallala Aquifer- in the high planes of the US. Has the largest groundwater deposit in the world. Water is being withdrawn from it faster than nature can replace it. E. Global Water Problems a. Amount of freshwater on the planet can meet human needs but it is unevenly distributed and some places lack stable runoff a.i. Stable Runoff- The share of runoff from precipitation that can be depended on every month b. Water and Climate Change b.i. Climate change affects the type and distribution of precipitation b.ii. Potential issues- reduced snowfall will impact water resources downstream and sea level rise will cause saltwater intrusion into drinking water supplies c. Drinking water Problems c.i. Many developing countries have insufficient water to meet drinking and household needs d. Population Growth d.i. Increase in population means an increase in the freshwater drinking requirements d.ii. Limits drinking water available d.iii. Limits water available for agriculture e. Sharing Water Resources Among Countries e.i. Rhine River Basin e.i.1. Countries upstream discharged pollutants into river e.i.2. Countries downstream had to pay to clean the water before they could drink e.ii. Aral Sea e.ii.1. Water diversion for irrigation has caused sea to become to saline f. Potential Volatile International Water Situations f.i. Jordan River f.ii. Nile River F. Water Management a. Maine goal is to provide sustainable supply of high-quality water with: a.i. Dams and Reservoirs a.i.1. Ensure year round supply of water with regulated flow a.i.2. Generate electricity a.i.3. Provide recreational activities a.i.4. Alter the ecosystem a.i.5. Reduce sediment load a.ii. Water Diversion Projects a.ii.1. Waters are diverted to areas that are deficient a.ii.2. Much of Southern CA receives its water supply from diverted water from Northern CA. a.ii.3. Controversial and expensive a.iii. Desalinization a.iii.1. Removal of salt from ocean or brackish water a.iii.2. Can be done by distillation or reverse osmosis a.iii.3. Very expensive G. Water Conservation a. Reducing agricultural waste a.i. Agriculture is inefficient with water a.ii. Microirrigation- irrigation that conserves water by piping it to crops through sealed systems, Also called drip irrigation a.iii. Low energy precision application irrigation LEPA a.iv. Geographic information systems irrigation GIS b. Reducing Industrial Waste b.i. Stricter laws provide incentive to conserve water b.ii. Water scarcity encourages further industrial recycling c. Reducing Municipal Water Waste c.i. Gray water- Water that has already been used for relatively non- polluting purpose such as showers, dishwashing and laundry. Can be used to flush toilets, water plants or car washing c.ii. Water saving household fixtures c.iii. Government incentives c.iv. Collecting and storing rainwater